honestly just depends on what kind of experience you want currently.
QSP is more complete, HTML is the one still being updated.
they both have bugs of course --the HTML version has more right now due to Snekk still figuring out Twine, the QSP version has a couple major problems that are a major contributing factor for the switch to Twine-- so it's more a pick your poison kinda deal?
playing the QSP would probably be a good way to get a basic feel for the game, since it's the earlier version, the HTML version is kind of barebones since it doesn't have all the QSP content in yet.
I personally enjoy them both tho.